Vaginal microbiota and human papillomavirus (HPV): bacteria to the rescue

Vaginal human papillomavirus (HPV) is the most common sexually transmitted infection (STI). It is usually asymptomatic. Most of the time, the body eliminates these viruses by itself. However, they can persist in some women, putting them at risk of infections that can lead to cervical cancer. The fourth most common type of cancer among women (sidenote: https://www.who.int/fr/news-room/fact-sheets/detail/human-papillomavirus-(hpv)-and-cervical-cancer ) , cervical cancer is currently incurable and represents a major public health concern.

Dysbiosis of the vaginal microbiota

The risk factors for persistent HPV infections are known: they consist of behavioral (vaginal douching, sexual intercourse) and biological (bacterial vaginosis, bacterial vaginosis, sexually transmitted infections) factors that disturb the vaginal microbiota (dysbiosis). To date, most studies have focused on the link between dysbiosis and precancerous or cancerous lesions of the cervix, but none on the identification of a microbial signature of persistent HPV infection that can be detected before lesions appear, thereby preventing progression to cancer.

Probiotics for prevention?

The analyses showed that HPV infection is associated with a disturbance of the vaginal microbiota, with differences observed between the NC group and groups P and C. The analyses also showed that HPV infection is characterized by depleted bacterial richness and lower bacterial diversity.  Current or past infection is associated with an increase in Firmicutes and Actinobacteriota, and a decrease in Proteobacteria. The authors believe that this dysbiosis facilitates infection by the virus, whereas an increased abundance of vaginal Proteobacteria is thought to stabilize the microbiota. While the vaginal microbiota of all three groups were dominated by lactobacilli, their abundance was even greater in patients who had eliminated the virus (group C) than in NC patients. The researchers also observed a greater abundance of lactobacilli or bifidobacteria species depending on the type of virus eliminated, suggesting that these bacteria have a protective effect against different types of viruses. 

These findings have yet to be confirmed, but the researchers conclude that they pave the way for the development of probiotics which can be used to treat HPV infection early, before malignant lesions of the cervix appear.